The present invention relates to a new and improved construction of a stopping device for fiber material, particularly elongate or rope-like fiber material such as a sliver, roving or slubbing in a textile machine, more particularly a spinning machine. Such stopping device thus will be generally referred to hereinafter broadly as a slubbing stopping device whether the fiber material be a sliver, roving or slubbing or the like. The present invention also relates to an improved energy storage device, particularly for use with the slubbing stopping device.
U.S. Pat. No. 4,683,712, granted Aug. 4, 1987 and the cognate German Patent Publication No. 3,526,309, published Jan. 29, 1987 may be cited as one of the many examples of a stopping device for a sliver, typically referred to as a slubbing stopping device in the case of a ring spinning machine. In the therein disclosed slubbing stopping device a compression spring is held in its stressed or loaded position by a latch, the latter being unlatched by an electromagnet so that the spring presses a movable clamping element upwards against a stationary clamping surface in order to clamp the slubbing. It will be apparent that such an electromagnet requires a high current strength in order to overcome the latching forces. In order to avoid overloading the energy source in the event there are used a plurality of slubbing stopping devices which are simultaneously triggered, a capacitor is proposed as an energy storage device for each slubbing stopping device in the aforementioned prior art system. However, a considerable outlay is necessary in terms of the electrical circuitry for the charging and storage circuit.
In U.S. Pat. No. 4,727,713, granted Mar. 1, 1988 and the cognate German Patent Publication No. 3,606,609, published Sept. 3, 1987, the object of which is to ensure certain triggering of the slubbing stopping device when necessary, as a result of the electromagnetic triggering operation the slubbing is clamped against a non-driven preliminary drafting roller of a drafting arrangement. For triggering purposes, a stationary electromagnet surrounds a movable permanent magnet and so attenuates the holding force or retentivity of the permanent magnet that the permanent magnet can no longer produce the required holding action. In other words, the magnetic field of the permanent magnet is attenuated in the direction of polarity reversal. The permanent magnet must continually overcome the tension or loading force of a spring which is intended to displace an actuating rod and thus a clamp segment, so that this permanent magnet has to be made relatively large. The coil enclosing the permanent magnet is even more voluminous or bulky, so that for cost reasons alone a triggering device or system of this kind cannot be considered for practical use. The subsequent publication "Zinser Novum 8" gives an indication of how difficult it really is to attain a practical embodiment of this allegedly certain triggering system, this publication describing a quite conventional actuation of a slubbing stopping device by means of a solenoid and a pull rod released thereby.